The Rosette Nebula, designated as NGC 2237-9, is a very large celestial cloud of dust and gas that extends over an area of about 1 degree of the sky.  This impressive object lies in the constellation Monoceros at a distance of approximately 5,000 light years from the Earth. In the center of the "Rose" lies the open cluster NGC 2244.  These young massive stars are the illuminating source exciting the gasses in the nebula to glow in much the same way as a neon light.

The image above is known as a mapped, or false, color image and was acquired using narrowband filters.  It was assembled using the standard Hubble Palette with SII mapped to red, Ha mapped to green and OIII mapped to blue.